最重的一件喪服，禮書寫得很具體：「喪服，斬衰裳，苴絰杖，絞帶，冠繩纓，菅屨者。」——粗麻做的上衣下裳，邊不縫；苴麻做的腰帶；一根竹杖；絞麻的帶子；麻繩做帽纓；草鞋。然後是穿它的人：諸侯為天子，臣為君，父為長子，出繼給他人作後嗣的人；妻為夫，妾為君，未嫁的女兒為父。三年。
五個名目，不止五等
「五服」是五個名目：斬衰、齊衰、大功、小功、緦麻。《儀禮·喪服》正是按這個次序往下排：斬衰裳（斬衰）——疏衰裳齊（齊衰）——大功布衰裳（大功）——繐衰——小功布衰裳（小功）——緦麻。名目五個，等級不止五個：斬衰三年；齊衰有三年、期（一年）、不杖期、三月幾等；大功九月，還分殤服與成人服；小功五月；緦麻三月。另有一等「繐衰」——諸侯之大夫為天子，「既葬除之」。
只舉齊衰裡的幾種：三年者，「父卒則為母，繼母如母，慈母如母，母為長子」；期者，「父在為母，妻，出妻之子為母」；不杖期者，「祖父母，世父母，叔父母」，還有昆弟、眾子、昆弟之子；三月者，「寄公為所寓」「庶人為國君」「曾祖父母」。同一件「齊衰」，落在不同關係上，服期就不同。
服制是怎麼排的
喪服篇的排法是：每一等喪服下面掛一串人。不是按感情排，是按關係與身分排——父、母、夫、君、長子、祖父母、世叔父母、姑姊妹、從父昆弟……同一等裡既有「為父」也有「為君」。為什麼？《禮記·喪服四制》說：「其恩厚者其服重，故為父斬衰三年，以恩制者也」；「資於事父以事君，而敬同，貴貴尊尊，義之大者也，故為君亦斬衰三年，以義制者也」。一套是恩，一套是義，兩條線並進。
這張表的座標是親屬距離。《禮記·喪服小記》給了一句骨架：「親親以三為五，以五為九，上殺、下殺、旁殺，而親畢矣。」——從自己數上去、數下去、數到旁邊，服隨親疏遞減，減到盡頭就沒有服了。所以五服是從一個中心往外推的同心圈，不是身分等級。
五等落到布、哭、食、住
《禮記·間傳》把五等落成看得見、摸得到的東西。先是布：「斬衰三升。齊衰四升、五升、六升。大功七升、八升、九升。小功十升、十一升、十二升。緦麻十五升去其半。」——布以「升」計，升數越小布越粗，最重的喪服最粗。喪服篇末的記另有一組數字：斬衰三升、三升有半，其冠六升；齊衰四升，其冠七升；大功八升或九升；小功十升或十一升。與《間傳》不完全一致，照錄，不合併。接著是哭：「斬衰之哭，若往而不反；齊衰之哭，若往而反；大功之哭，三曲而偯；小功、緦麻，哀容可也。」接著是不食：「斬衰三日不食，齊衰二日不食，大功三不食，小功、緦麻再不食。」接著是住：「父母之喪，居倚廬，寢苫枕塊……齊衰之喪，居堊室……大功之喪，寢有席；小功、緦麻，床可也。」
三年之喪為什麼是三年？《禮記·三年問》說：「三年之喪，何也？曰：稱情而立文……三年者，稱情而立文，所以為至痛極也。」又說「三年之喪，二十五月而畢」——三年之喪，二十五個月就結束；之所以加倍，是「加隆焉爾也，焉使倍之，故再期也」；篇末引孔子曰：「子生三年，然後免於父母之懷。夫三年之喪，天下之達喪也。」《禮記·服問》則給了一句總綱：「罪多而刑五，喪多而服五。上附下附，列也。」——刑罰五等，服制五等，都靠「往上附、往下附」來歸類。
禮書規定，不是執行記錄
這一層必須說清：《儀禮》是禮書，喪服是一張規定表。它規定某類人為某類人服某服、服多少個月，不記錄誰真的穿了、穿了多久。實際執行的程度、地域差別、時代變化，這兩頁都不回答。所以不能寫「周代人都服三年喪」——只能說禮書這樣規定。
這張表主要涵蓋貴族與士的親屬關係。士以下的人在篇中只在個別條目裡露面——「庶人為國君」是一條，「公士、大夫之眾臣為其君布帶、繩屨」是一條；除此之外，禮書對他們的日常服制幾乎沒有材料。禮書規定的對象，不等於當時全體人口。
材料裡沒有的
沒有一份實際服喪的記錄；沒有「二十五月而畢」這套期數被執行的證據；沒有庶人、奴婢的完整服制表；沒有各地差異。能讀到的《儀禮·喪服》頁有經與記，沒有傳（問答式的解釋），本文只用經與記。喪服篇本身也有難讀與異文：殤服分長殤、中殤、下殤，期數各異（大功條目裡「其長殤皆九月，纓絰；其中殤，七月，不纓絰」），繐衰只繫在諸侯之大夫為天子一條上，都是讀的時候要留意的地方。
所以五服是一張以親屬距離為橫軸、以身分為縱軸的表。它的影響力在後世——法律與禮俗都用它來定親疏；但它本身是禮書條文。讀它最該記住的不是「五種心情」，而是五種布、五種杖、五種居處、五種不食的天數：禮把哀痛拆成了可以規定的動作。
延伸閱讀：九世之亂：《史記》裡的一段商代繼統 · 五十名博士弟子：漢太學的初置 · 「卜其晝，未卜其夜」：一場酒、一個孩子與兩套問法
參考來源與延伸閱讀
- 《仪礼·丧服》（战国至汉初成书；维基文库本，未与点校本复核） — The table itself. It opens with the heaviest grade: 'Mourning dress: sackcloth upper and lower garments with unhemmed edges, a coarse hemp belt and staff, a twisted band, a cap with rope strings, straw sandals' (喪服，斬衰裳，苴絰杖，絞帶，冠繩纓，菅屨者) — and under it a list of persons: the feudal lords for the Son of Heaven, a subject for his lord, a father for his eldest son, one who has become another's heir; a wife for her husband, a concubine for her lord, an unmarried daughter for her father: for three years. The chapter then works down by grade: a trimmed-hemp version for three years (father deceased, then for mother; stepmother and foster mother as mother; mother for eldest son), a one-year version (father alive, for mother; for wife; a divorced wife's son for his mother), an unstaffed one-year version (grandparents, uncles and aunts, elder and younger brothers, brothers' sons…), three months (the exiled lord for his host, a commoner for his ruler, great-grandparents…), then the nine-month, five-month and three-month grades, and an extra grade of fine hemp, worn by a feudal lord's minister for the Son of Heaven 'and removed after the burial'. It is a schedule of who wears what for whom: it gives no record of anyone actually wearing it. The page used here carries the chapter's schedule and its closing notes (記) with cloth measurements, but not the tradition (傳) that explains individual clauses in question-and-answer form; this article cites only the schedule and the notes.
- 《礼记》间传、三年问、服问、丧服小记、丧服四制（战国至汉初成书；维基文库本，未与点校本复核） — The commentary and rationale, in several chapters. 間傳 turns the five grades into cloth and behaviour: the cloth is reckoned in sheng — three for the heaviest, four to six for the trimmed grade, seven to nine for the nine-month, ten to twelve for the five-month, fifteen halved for the three-month; the wailing differs by grade (the heaviest 'goes and does not return'); the fasts differ (three days without food for the heaviest, two for the next, three skipped meals for the nine-month, two for the lightest); and the dwelling differs (a thatched hut with a straw mat and a clod for a pillow for parents, a mud-plastered room for the trimmed grade, a mat for the nine-month, a bed for the lightest). 三年問 explains the three years: 'the three years' mourning is finished in twenty-five months' (三年之喪，二十五月而畢), 'it is doubled because it is made heavier' (加隆焉爾也，焉使倍之，故再期也), and quotes Confucius on the three years a child is carried. 服問 gives the summary sentence: 'crimes are many but punishments five; mourning is many but its grades five' (罪多而刑五，喪多而服五). 喪服小記 gives the kinship frame: 'kin by three, extending to five, extending to nine; cut above, cut below, cut to the side, and kinship is exhausted' (親親以三爲五，以五爲九，上殺、下殺、旁殺，而親畢矣). 喪服四制 explains that the heaviest grade is worn for a father 'by grace' and for a lord 'by right' (以恩制者也…以義制者也), and that a father alive means a one-year grade for the mother, 'for there are not two honoured ones' (見無二尊也). The other chapter pages are https://zh.wikisource.org/wiki/禮記/三年問, /禮記/服問, /禮記/喪服小記 and /禮記/喪服四制. All are prescriptions; none records an actual funeral. Note that the Yili's closing notes and the Liji's 間傳 give slightly different sheng counts for the same grades; this article records both rather than merging them.
